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https://issues.apache.org/jira/browse/HDFS-6581?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14143029#comment-14143029
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Arpit Agarwal commented on HDFS-6581:
-------------------------------------
Micro-benchmark to verify that SCR performance does not suffer with this
feature.
Numbers below for short-circuit reads of 1GB file, Block Size = 256MB, mean
throughput over 1000 iterations of reading the file fully.
||IO Size||Read Throughput Lazy Persist off (MB/s)||Mean Read Throughput Lazy
Persist on (MB/s)||
|64K|2661|2611|
|1M|2267|2354|
For comparison, here is the read throughput *without Short-circuit reads*:
||IO Size||Read Throughput (MB/s)||
|64K|1470|
|1M|1275|
> Write to single replica in memory
> ---------------------------------
>
> Key: HDFS-6581
> URL: https://issues.apache.org/jira/browse/HDFS-6581
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode
> Reporter: Arpit Agarwal
> Assignee: Arpit Agarwal
> Attachments: HDFS-6581.merge.01.patch, HDFS-6581.merge.02.patch,
> HDFS-6581.merge.03.patch, HDFS-6581.merge.04.patch, HDFS-6581.merge.05.patch,
> HDFS-6581.merge.06.patch, HDFS-6581.merge.07.patch, HDFS-6581.merge.08.patch,
> HDFS-6581.merge.09.patch, HDFSWriteableReplicasInMemory.pdf,
> Test-Plan-for-HDFS-6581-Memory-Storage.pdf
>
>
> Per discussion with the community on HDFS-5851, we will implement writing to
> a single replica in DN memory via DataTransferProtocol.
> This avoids some of the issues with short-circuit writes, which we can
> revisit at a later time.
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